The present invention relates to an improved apparatus for measuring the eccentricity of eccentric bearing faces, and more particularly, connecting rod bearing faces.
A prior device for measuring the eccentricity of eccentric bearing faces is disclosed in German Disclosure Document DE-OS No. 31 47 424. In this device, a length measurement gauge is retained in a slide which allows lateral movement of the length measurement gauge. A drive arrangement laterally guides the slide and gauge, and moves sinusoidally. The amplitude and phasing of this motion are adjustable with respect to the rotary position of the eccentric bearing face. A problem associated with this apparatus is that the arrangement that generates the control function is complex and extremely difficult to adjust. A residual error always subsists, and is compounded with the measured radial dimensions and thus the measured eccentricity of a bearing face.
Other apparatus for measuring the out-of-round of eccentric bearing faces are disclosed in brochures of the Adcole Corporation of Waltham, Mass. concerning the Adcole Model 910, 1200 and 1300. These apparatus employ a measuring rule at the end of a measurement cam which bears tangentially on the eccentric bearing face to be measured. The point of contact migrates backward and forward as the crankshaft rotates. A disadvantage of these apparatus is that the measuring rule must be long relative to the eccentricity of the bearing face to be measured. The measuring rule must also be perfectly straight and perfectly perpendicular to the direction of measurement. As a result, these apparatus are very costly and complex to maintain. Measurements contain residual error, because the conditions of perfect accuracy can never be met. Another disadvantage of the Adcole apparatus is that the measuring rule suffers wear as a result of friction.